For many years, wall plates for electrical devices, such as switches, receptacles, and the like, have been made from thermosetting materials, such as urea and urea-formaldehyde resins and the like. These materials are inexpensive and relatively easy to mold into wall plates, but have the disadvantage of being quite brittle and requiring the use of manufacturing methods that produce environmentally unfriendly by-products that are difficult and/or expensive to dispose of.
A relatively small number of wall plates has been manufactured from thermoplastic material. Thermoplastic materials are less brittle than thermosetting materials and can be produced by manufacturing methods that are cleaner than those required for the manufacture of thermosetting materials. However, thermoplastic materials, while strong, are not nearly as rigid as thermosetting materials of the same thickness, and there has been some resistance to the use of thermoplastic wall plates because they, although unbreakable, have a greater flexibility than wall plates made from thermosetting material, and therefore appear less sturdy to customers.
It is known to provide wall plates with openings for receiving mounting screws having webs therein for holding the mounting screws during assembly. However, it has been the universal practice to sell such wall plates with the mounting screws separately packaged, for example in a separate plastic envelope, included along with the wall plate. This increases the cost of packaging, and also the difficulty of installing the wall plate since the screws must be removed from the separate package, manually inserted into the opening, and subsequently tightened to fix the wall plate in position.
It is an object of this invention to provide an improved wall plate that overcomes one or more of the foregoing disadvantages of wall plates heretofore known.
More particularly, it is an object of this invention to provide a wall plate fabricated from thermoplastic materials that is more rigid than those heretofore known.
It is another object of this invention to provide a wall plate made from thermoplastic materials that has an array of reinforcing ribs on a rear surface of the wall plate that at once stiffen the wall plate and also provide a desirable rigid appearance to consumers, thereby influencing the purchasing decision.
It is still a further object of this invention to provide a thermoplastic wall plate having a screw opening with screw retaining webs therein in a package in which a screw is disposed within the opening, held captive by the web at the time of sale to eliminate the need for separate packaging of the screws, and to greatly simplify installation of the wall plate.
Briefly stated, and in accordance with a presently preferred embodiment of the invention, a reinforced thermoplastic wall plate with captive screw comprises a generally rectangular body of thermoplastic material having a smooth surface on a front side, a raised peripheral rim on an opposite rear side, a plurality of reinforcing ribs extending outwardly from the surface of the wall plate on the rear side extended to a height no greater than the height of the raised peripheral rim, a mounting screw opening extending from the front side to the back side, a web within the mounting screw opening, and a screw retained in the opening by the web, a thread of the screw being engaged by an edge of the web.
In accordance with another aspect of this invention, a reinforced thermoplastic wall plate comprises a body formed from nylon.